Test: NKE THr – room sensor for recording temperature, humidity and light intensity

December 13, 2018

The nke Watteco THr room sensor is suitable for recording temperature, humidity and light intensity values. The primary energy source is a solar cell. An internal battery allows autonomous operation of up to 3 months. The sensor can be configured completely via LoRaWAN downlinks.

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Product name: THr Sensor
Category: Room sensor
Developer: nke Watteco
Rue Gutenberg
ZI Kerandré
56700 Hennebont

The most important features at a glance

    • LoRaWAN, Class A
    • Temperature
      • Measuring range: -40°C to +120°C
      • Resolution: 1/100°C
      • Accuracy:
        • +/-0.5° (0° to +65°C)
        • +/-1° (-30°C to 0°C and +65°C to +90°C)
        • +/-2° (< -30°C and> +90°C)
    • Humidity
      • Measuring range: 20% to 80%
      • Resolution: 4% RH
      • Accuracy:
        • +/- 3%rH (20%rH to 80%rH)
        • +/- 5%rH (< 20%rH and > 80%rH)
    • Ambient light intensity indicator: 0% – 100%
    • Configurable transmission cycle
    • Supports ABP and OTAA
    • Configurable via downlinks
    • Batch reports for faster query intervals and compressed data transmission
    • Power supply:
      • 3.6V / 1100mAh lithium battery
      • Internal battery for solar buffering
      • Operating voltage via solar from 200Lux ambient light
    • Internal antenna:
    • Certifications: RoHS, CE, FCC

 

Unboxing: housing and processing

THr frontal viewTHr back side

The THr sensor is enclosed in a housing for wall mounting. The dimensions are 81mm x 73mm x 20mm. The back plate of the housing can be fixed with two screws. A 3.6V / 1100mAh lithium battery is integrated for operation without ambient light. The THr can generate the operating voltage completely via the solar cell when the ambient light is at least 200 LUX. An internal battery buffers the solar power supply.

Connections

THR nke Watteco room sensor buttons

The THr sensor wo has an info LED, a user button and a reset button. On the board it also has an on/off switch, which is accessible after removing the back plate.

Configuration and operation

The THr sensor can be completely configured, in the usual nke Watteco way, via LoRaWAN downlinks. Also, all settings can be read again later. The following, inter alia, is supported:

  • Reading the software versions on the sensor
  • Reading out the settings regarding the transmission intervals and the behavior of the inputs and outputs
  • Reading and modifying LoRaWAN settings, such as OTAA parameters, uplink types (confirmed / unconfirmed), re-joining intervals and timeouts, data rates, etc.
  • Reading the battery voltage

The temperature, humidity and light intensity messages can be configured flexibly and independently. The THr sensor offers the possibility to store individual fixed message intervals for each of the 3 measured values. Alternatively, a delta can be defined, so that if the delta exceeds or falls below the last measured value, a message is immediately sent to the LoRaWAN network server.

In order to reduce the frequency and size of the sent LoRa messages, all hree measured values ​​can be summarized in a batch report and sent in compressed form. With the help of the batch report, it is possible to shorten the measuring intervals significantly without running the risk of violating the LoRaWAN Duty Cycle.

When shipped, the sensor is configured as follows: The sensor sends the temperature and relative humidity every 8 hours.

“Hands-on”: the how-to in single steps

Although all the settings stored in the sensor can be queried by appropriate downlinks, this must be done separately for each of the 3 measurement types. Therefore, it is advisable to reset this unknown settings of a sensor. Otherwise, uplink messages from old / unknown settings can quickly become confusing and generate a lot of data transfer.
nke Watteco sensors receive the downlinks on port 125, unless otherwise stated.

In order to reset a THr to the standard factory settings (see above), the “user button” must be pressed according to the following scheme: press and hold twice for about 7 seconds. The red / green LED flashes rapidly during this process.

To delete all settings related to the temperature, humidity or light intensity measurements and the sending of messages (uplinks), the following downlink can be sent:

0x 11 50 00 50 02 03

There is no confirmation for this downlink.

To read out the current temperature value, the following downlink can be sent:

0x 11 00 04 02 00 00

The answer (uplink) on this looks like this:

0x 11 01 04 02 00 00 00 29 0A 0A

The current temperature value in this example is 25.7 ° C
Hex 0A0A = Dec 2570. The actual temperature is then 1/100 of the transferred value, ie 25.7 ° C

Configuration of automatic reports

TTo receive an uplink message of thetemperature once a dayplus an immediate notification as soon as the temperature has changed by more than 10°C between two measuring points, the following downlink can be sent:

0x 11 06 04 02 00 00 00 29 00 00 85 A0 03 E8

As a sign of successful configuration, the sensor sends the following response (uplink):

0x 11 07 04 02 00 00 00 00

In order to receive an uplink message of thehumidity every 3 hours and additionally an immediate notification as soon as the humidity has changed by more than 20% between two measuring points, the following downlink can be sent:

0x 11 06 04 05 00 00 00 21 00 00 2a 30 07 d0

As a sign of successful configuration, the sensor sends the following response (uplink):

0x 11 07 04 05 00 00 00 00

In order to receive an uplink message of the light intensity every 15 minutes and additionally an immediate notification as soon as the light intensity has changed by more than 10% between two measuring points, the following downlink can be sent:

0x 11 06 00 0c 00 00 55 39 00 00 80 0f 41 20 00 00

As a sign of successful configuration, the sensor sends the following response (uplink):

0x 11 07 00 0c 00 00 00 55

Conclusion

The nke Watteco THr can be configured very extensively. In addition to the numerous LoRaWAN settings, you can make individual settings for the uplink messages, the frequency of the measurement and the notification intervals for the measured values ​​temperature, humidity, light intensity and battery voltage.

This also means, however,that a separate uplink must be sent for each of the 3 or 4 measurement types. It would be better if all 3 or 4 measured values ​​could be sent together in one message.

In order to reduce the number of configurations as well as the amount of uplink messages, the THr supports the configuration of batch reports. Here, the individual measured values ​​are collected on the sensor and compressed at a later time sent as an uplink message. This makes it possible to monitor one or more measurement types in relatively short time intervals and still comply with the LoRaWANDuty Cycle, ie the allowed number of uplink messages per hour.

The very extensive configuration options via downlinks allow a simple and always changeable configuration of the sensor, but also require some familiarization with the configuration terminology. The manufacturer facilitates the work by a very good and extensive documentation with numerous configuration examples. Anyone who has already configured other Watteco sensors will find their way around quickly.

 

Reference

We are official Watteco Distributors. The device is available in our IoT marketplace.

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